Electronic security systems are well known in the prior art. Such security systems are typically used to control access through locked doors and the like to a particular area or room in a building. Such security systems are frequently used in industrial applications to limit access to a particular area only to authorized individuals. Security systems are also frequently used in both commercial and non-commercial applications. An example of a non-commercial application are the security systems which are frequently used in connection with garage door openers, gate controllers and door controllers in and around the home.
Typically, the security systems comprise a receiver which is responsive to an encoded radio frequency signal and a transmitter which is capable of transmitting the encoded radio frequency signal. In both the transmitter and the receiver, known in the prior art, the encoding of the radio frequency signal is controlled by manually flipping switches. Due to the small size of the transmitter units (they are usually hand held) and due to the fact that usually eight to sixteen switches are used to provide a sufficient number of different possible codes (for security purposes), the switches tend to be quite small in size. Generally speaking, identical switches are found in the receiver unit. Thus, in the prior art, it was necessary for a home owner (or other user of the security system) to manually flip the switches in both the receiver and hand held transmitter units to the identical code in order to "program" the devices.
These prior art techniques have several disadvantages. First, home owners and other users not infrequently neglect to "program" their transmitters and receivers (i.e., flip the switches to some code) due to a perceived complexity in carrying out the programming and, therefore, the units, as installed, are essentially unprogrammed. Second, the code can be easily read by third parties who are lent the hand held transmitter units (usually, all one must do to read the code is to open the case of the transmitter, which is easy to do since the case must be opened to change the unit's battery, and then note the position of the switches). Therefore, the security of the devices can be relatively easily breached.
There is a need, therefore, for security devices which can be easily programmed with a security code but which are relatively secure in concealing the security code from unauthorized parties.